Given the popularity of the Internet, information-related commodities have become popular products that link the previous century with the present century. The simple electronic notebooks that have been evolving for years, helping people manage their lives and memorize trivialities, have been gradually replaced by PDAs. PDAs have become a technological upstart as well as the secretary of business people everywhere.
A PDA is a palm-sized computer that works as a digital personal assistant. In the beginning, the basic functions of the PDA included no more than a schedule, an agenda, a notepad and an address book. The evolution of the PDA has enabled it to be connected to a computer for synchronous data transmission, or even to be installed with various types of application software so as to expand its functions. The expanded functions, which are too numerous to list, include receiving or sending e-mail online, browsing shares-related information, recording revenue and expenditure, browsing e-books, games, spreadsheets, databases, information about daily life and wireless communication, etc. A PDA works more efficiently than a hired assistant, provided that a user makes good use of the functions of the PDA s/he owns.
However, owing to its aforesaid diversified functions, the PDA is usually quite bulky and thus inconvenient to carry. As a result, users who hold a PDA for a long time may get a sore arm. There are now designs that employ another expansion device to carry out some of the functions of PDAs, for example, an external keyboard, an external modem, and an external Bluetooth fixture, etc. However, when connected to a PDA, none of these kinds of external devices can form a binary PDA that is easy and convenient to use (the protruding part prevents ease of use) and good looking.
For the aforesaid reasons, the invention puts forward a PDA with an expansion back case that embodies diversified, but seldom used, functions, so that the body is smaller and lighter. Thus, it will be easier for a user to hold the PDA and s/he may choose to carry either the binary PDA or just the body so as to enhance the flexibility of the use of PDA. In addition, putting the body and the expansion back case together produces no protruding part that can affect the ease of use, and does not detract from the appearance of the binary PDA.